The corporate-ir site is actually part of Thomson Reuters and our press releases end up there.
If a particular AWS release includes both a press release and a blog post, the press release goes out first.
After the release shows up in public I publish the blog post and submit it to HN.
Quantum fluctuations of the universe caused the press release to get more votes than the blog post and that's why it's on the front page.
This is actually a very interesting conversation. It is interesting to see that the post on the AWS blog, hosted on TypePad, is seen as more official than the press release.
tl;dr PR newswire (BUS) comes first @ 8:54, it hit Bloomberg News wire four seconds after release. Amazon blog wasn't until 9:17, followed by others such as TechCrunch @ 10:11.
Also i doubt that typepad would be as trusted if your blog wasn't as popular. If it were some company whose blog i've never read before, i wouldn't be inclined to trust announcements from typepad. but everybody here knows the aws blog.